Disclosures: Tidemandsen reports receiving speaker fees from Teva Pharmaceutical Industries and a grant from Novartis. Please see the study for relevant financial information from all other authors.
According to a study published in The Journal of Allergy and Clinical Immunology: In Practice.
Low-grade inflammation could be a common pathway for asthma and these losses, Casper Tidemandsen, MD, Ph.D., from the Department of Respiratory Medicine at Copenhagen-Hvidovre University Hospital in Copenhagen, Denmark, and colleagues wrote in the study.
The researchers used national health registers to examine the records of 1.3 million women in Denmark. Among them, 128,553 women aged 6 to 45 had filled at least two prescriptions for asthma medication in the 12 months between 1977 and 2019.
Compared to non-asthmatic women, asthmatic women had a higher likelihood of having one miscarriage (adjusted OR = 1.05; 95% CI, 1.03-1.07), two miscarriages (aOR = 1 .09; 95% CI, 1.05-1.13), three or more losses (aOR = 1.18; 95% CI, 1.11-1.24) and recurrent miscarriage (RPL; aOR = 1.19; 95% CI, 1.12-1.27).
Women with early asthma, defined as onset between 6 and 15 years of age, had an aOR of 1.47 (95% CI, 1.24-1.72) for three or more pregnancy losses.
Additionally, women with uncontrolled asthma—based on their use of 400 or more doses of short-acting beta-agonists (SABAs) per year—had an aOR of 1.6 (95 CI %, 1.16-2.16) for three or more pregnancy losses compared to women with controlled asthma.
According to the researchers, women with asthma had significantly increased risks for all pregnancy loss outcomes except for two or more pregnancy losses in the second trimester and stillbirth.
Apart from pregnancy loss, asthmatic women also had a higher risk of complicated delivery after RPL (aOR = 1.43; 95% CI, 1.17-1.74) compared to non-asthmatic women.
This association between asthma, particularly at a young age, and the number of pregnancy losses was unidirectional, the researchers found.
Often, early asthma is associated with a specific type 2 asthma and inflammation phenotype, typically characterized by eosinophilic inflammation, which may be more closely related to pregnancy losses, the researchers continued.
Women who experienced asthma onset before their first pregnancy saw a stronger association with three or more pregnancy losses than women who developed asthma after their first pregnancy, suggesting that the asthma itself or a shared immunological background could be the cause of asthma.
The study further revealed that 28.3% of women with asthma and 36.7% of women without asthma had never had a pregnancy (aOR=0.93; 95% CI, 0.92-0.94 ).
However, the researchers cautioned that the population included women with infertility, chronic conditions that made pregnancy impossible, and women who had actively decided not to have children, making conclusions difficult.
Still, the researchers said the strongest associations between asthma and pregnancy loss occurred in women with a higher likelihood of having an immunological history, suggesting the need for future studies to identify the mechanisms. the origin of this relationship.
The researchers also noted the need to control asthma before and during pregnancy in women of childbearing age, with particularly close monitoring of women with asthma and LPR during childbirth.